A-M baby

Task/Knapsack-problem-Bounded/Haskell/knapsack-problem-bounded-1.hs

@@ -0,0 +1,15 @@
+inv = 	[("map",9,150,1), ("compass",13,35,1), ("water",153,200,2), ("sandwich",50,60,2),
+	("glucose",15,60,2), ("tin",68,45,3), ("banana",27,60,3), ("apple",39,40,3),
+	("cheese",23,30,1), ("beer",52,10,3), ("cream",11,70,1), ("camera",32,30,1),
+	-- what to do if we end up taking one trouser?
+	("tshirt",24,15,2), ("trousers",48,10,2), ("umbrella",73,40,1), ("wtrousers",42,70,1),
+	("woverclothes",43,75,1), ("notecase",22,80,1), ("sunglasses",7,20,1), ("towel",18,12,2),
+	("socks",4,50,1), ("book",30,10,2)]
+
+knapsack = foldr addItem (repeat (0,[])) where
+	addItem (name,w,v,c) old = foldr inc old [1..c] where
+		inc i list = left ++ zipWith max right new where
+			(left, right) = splitAt (w * i) list
+			new = map (\(val,itms)->(val + v * i, (name,i):itms)) old
+
+main = print $ (knapsack inv) !! 400

Task/Knapsack-problem-Bounded/Haskell/knapsack-problem-bounded-2.hs

@@ -0,0 +1,11 @@
+import Data.Array
+
+-- snipped the item list; use the one from above
+knapsack items cap = (solu items) ! cap where
+	solu = foldr f (listArray (0,cap) (repeat (0,[])))
+	f (name,w,v,cnt) ss = listArray (0,cap) $ map optimal [0..] where
+		optimal ww = maximum $ (ss!ww):[prepend (v*i,(name,i)) (ss!(ww - i*w))
+					| i <- [1..cnt], i*w < ww]
+		prepend (x,n) (y,s) = (x+y,n:s)
+
+main = do print $ knapsack inv 400